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Biomedical subjects

S A Feig

Publications and source records attributed to S A Feig.

At least 217 records · Page 12Linked to original sources
PubMed1972

Energy metabolism in human erythrocytes. II. Effects of glucose depletion.

Normal red cells were incubated in the absence of glucose to develop a system in which total adenosine triphosphate (ATP) turnover could be assessed. After 1 hr, the triose pool had been completely consumed. Thereafter, the metabolism of 2,3-diphosphoglycerate (DPG) to pyruvate and lactate was the sole significant source of ATP synthesis.10(-3)M CuCl(2), which did not enter the cells, diminished ATP utilization by more than 50%. This could be only partially attributed to the inhibition by copper of residual acylation and cation pumping, which were already reduced by glucose depletion. Other membrane enzymes, which presumably function in the maintenance of membrane integrity, must, therefore, use a significant portion of erythrocyte ATP. The behavior of glucose-depleted red cells with respect to cation transport was complex. The addition of ouabain did not decrease ATP utilization in these red cells. Ouabain inhibitable potassium influx was nearly normal after triose depletion, but total potassium influx was decreased. In contrast, the ouabain inhibitable sodium efflux was markedly reduced after triose depletion, although the concentration of ATP was 70% of normal. The dissociation of monovalent cation pumping suggests that the energy for active sodium transport is derived from a specific source (such as the ATP produced by the phosphoglycerate kinase reaction) distinct from that for potassium transport.

Adenosine Triphosphate↗
PubMed1971

Energy metabolism in human erythrocytes. I. Effects of sodium fluoride.

Exposure of red cells to fluoride produces a variety of metabolic alterations, most of which are based upon the secondary effects of enolase inhibition, which reduces pyruvate synthesis and interferes with the regeneration of diphosphopyridine nucleotide (NAD). Adenosine triphosphate (ATP) is consumed in the hexokinase and phosphofructokinase reactions but is not regenerated since the deficiency of NAD limits glyceraldehyde phosphate dehydrogenase. ATP depletion in the presence of fluoride and calcium induces a massive loss of cations and water. Of the other known sites of ATP utilization, membrane-bound ATPase is inhibited by fluoride, but the incorporation of fatty acids into membrane phospholipids is unaffected until ATP is depleted. The addition of methylene blue to fluoride-treated red cells regenerates NAD, permitting triose oxidation and the generation of 3-phosphoglycerate and 2,3-diphosphoglycerate. Enolase inhibition is then partially overcome by mass action, and sufficient glycolysis proceeds to maintain the concentration of ATP. This in turn prevents the massive cation and water loss, and permits membrane phospholipid renewal to proceed. Membrane ATPase activity is not restored by the oxidant so that normal cation leakage remains unopposed by cation pumping in red cells exposed to the combination of fluoride and methylene blue.

Adenosine Triphosphatases↗
PubMedDate not supplied

Second malignant neoplasms after successful treatment of childhood cancers.

Improved treatment and supportive care have increased the survival of children diagnosed with cancer. This success has resulted in a growing population at risk of long-term complications of therapy, including secondary malignancy. These neoplasms may result from the direct effect of the modalities used in treatment of the primary tumor, more indirect effects of the treatment or supportive care, the genetic predisposition of the patient, or to interactions among these factors. The increasing success of cancer therapy is producing a rapidly growing population of patients at risk of second malignancy. This is a result of the increasing intensity of treatments and the increasing duration of survival, which provides the time to manifest the late effects of therapy. The concept that a patient is "cured" at some arbitrary time after treatment does not diminish the need for follow-up of all cancer survivors to identify and treat secondary malignancies. These risks have led to an increased effort to define phenotypic and genotypic categories of patients that may be cured with less intensive therapy and to develop molecularly targeted drugs that have fewer noxious effects on normal tissues.

Child↗
PubMedDate not supplied

Transplantation of hepatitis B surface antigen positive bone marrow.

We considered for bone marrow transplantation a boy whose only histocompatible donor was positive for hepatitis B surface antigen (HBsAg). He was conditioned for transplantation with cyclophosphamide and total body irradiation. Hepatitis hyperimmune gamma globulin was administered following the bone marrow infusion. Fourteen months after transplantation, the recipient remains a chronic HBsAg carrier, but he has neither developed fulminant liver disease nor has there been any evidence of graft failure.

Adolescent↗
PubMedDate not supplied

Non-calcified breast particles: a possible new marker of breast cancer.

Malignant and benign human breast tissue containing radiographic evidence of calcifications were studied by means of scanning electron microscopy and x-ray microanalysis. In addition to the well-known calcium-phosphorus deposits, discrete particles containing calcium with little or no phosphorus and calcium in combination with other elements were found. Moreover, particles containing elements other than calcium were observed. These include Al, Fe, Mg, Si, Cu, Zn, Cr, Ti, Ni, Pb, Au, Ag, Mo, Cl, I. Some of these "noncalcifications" contained a single element, others a combination of elements. These findings differ from the view that all breast particles are calcifications. Further study could lead to the development of new diagnostic techniques for the detection of breast cancer and/or chemotherapeutic agents.

Breast Neoplasms↗
PubMedDate not supplied

MR imaging of bone marrow in children.

The magnetic resonance (MR) images of the knees and hips of children with systemic diseases involving bone marrow were correlated with their marrow histology and compared with the images of asymptomatic normal children. In normal children the intensity of the MR signal from the bone marrow of the knees and hips was uniform throughout the metaphyses and diaphyses. In contradistinction the MR signal was uniformly diminished for the hypercellular marrow of patients with sickle cell anemia, was similar to normal for the hypocellular hyperfatty marrow of untreated aplastic anemia, and was nonuniform and patchy for leukemic marrow.

Adolescent↗
PubMedDate not supplied

Digital mammography.

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Breast Neoplasms↗